Separating mill



Jan. 13, 1942. A. SCHAICH SEPARATING MILL Filed NOV. 10, 1937 INVENTOR.

3 W H W 1L B Patented Jan. 13, 1942 2,270,143 SEPARATING MILL August Schaich, Dresden, "Germany Application November 10, 1937, Serial No. 173,780 In Germany March 3, 1937 2 Claims.

There are already known beating mills so connected with an air separator, that the separated coarse material falls back into the mill, which 1 however are only adapted for use in connection with softer goods and for obtaining a less fine separation.

Hard material to be ground and the necessity of obtaining extreme fineness of separation require grinding and separating devices of best technical construction, and their actions must be perfectly attuned to each other in order to obtain the greast possible fineness with best efilciency of the mill.

With the separating mill described hereafter the operations of the mill and the separator are so adapted to each other that all sources of mistake are, as far as possible, eliminated.

For this purpose the air used for separatin is so guided through the mill and the separating chamber, that it will carry the ground material from the grinding section into the separating chamber in a current adapted to the shape of the separating chamber, while avoiding uncontrolled whirls and currents. While the air-current passes in the shape of a spiral through the separating wheel-from outwards to the interior, the separated material, under the influence of three forces acting thereon (the sucking power, the driving power, the centrifugal power), will take a course deviating from the air spiral which carries the particles of materials, according to whether the sucking power or the centrifugal power preponderates, either towards the interior, to the fine ground material, or to the exterior, the coarser material which will have to be ground a further time.

For obtaining the correct formation of said air current spiral it i essential that the separating air, flowing in substantially the same direction as the separated material leaving the mill, take the latter up and carry it in a smooth current free of whirls tangentially along the separating wheel.

For this purpose there are arranged the curved air entrance pipe at the end of the grinding path as well as the damper guiding the air and subdividing the interior space.

In order to obtain an undisturbed air-currentspiral the plates r on the separating wheel are arranged in one or more series, the plates of each series which are progressively more advanced being located nearer to the axis of the separating wheel.

For obtaining a high degree of fineness, particularly when grinding hard material, it is necessary to make the beating edge, which the beating hammer pass as near as possible, very sharp, and in order to adapt the grinding to the material to be ground, said beating edge must be radially adjustable with respect to the rotor.

On the annexed drawing Figures 1 and 2 show a mode of construction of a grinding and separating mill according to the invention, with out excluding from the scope of the claims other similar, not shown constructions. I

Fig. 1 shows a section through a mill consisting of a separator and a grinding mill, and

Fig. 2 shows a partial longitudinal section according to the line A-B in Fig. 1 looking in the direction of the arrows.

a is the base, b a rotating grinding roller having beating hammers p, c is the air entrance pipe, 41 the supply-hopper, which ends with its supplychannel 0 in the grinding section e where said beating hammers p cooperate with casing anvil i to comminute the material. f is the separatin chamber, circumcluding the separator wheel 9. h is a fan, operated independently of the separating wheel, which sucks the air from the separating chamber I, through the separator-wheel g and forces it into an exit duct 1. i is an adjustable pivoted damper, which guides the aircurrent upwards in such a manner that it reaches the acting part of the separating wheel 9 without being disturbed. k is an adjustable beating edge, located at receiving edge s of casing anvil a (where the beating hammers p initially contact said casing anvil), at which the extracted particles again reach the acting ratio part of the grinding roller b.

In operation the material to be ground is fed into the supply hopper d, whence it is forced through its supply-channel o by the conveyor screw m into the space between the beating hammers p of grinding rotor b and the casing anvil a. It is then crushed and ground and carried along to delivery edge 11. of the casing anvil Thence its natural tendency to fly tangentially is reinforced by the column of air introduced through air entrance channel c. This column of air and mixed fine and coarse particles is sucked past adjustable pivoted damper i and is forced by the separator casing q to talre a generally spiral course within the separating chamber f. The finest-material is sucked with the air through between the revolving blades of the separating wheel g and blown by fan It into exit duct 1. The coarser material drops down into that part of the casing q between damper 1. and adjustable beating edge 1c, whence it is again series being furthest away from the axis of said wheel and, successively, the more advanced plate being nearer to the axis, and a damper located within said casing between said roller and said wheel and adjacent said roller.

2. In a grinding and separating mill of the 1 character described, a rotating grinding roller portion of said casing comprising a substantially V semicircular casing anvil adjacent said rotor and having a supply channel for theadmission of material to be ground and a delivery edge for delivering ground material where said roller separates from said semicircular casing anvil, an air entrance pipe substantially tangential to said roller at said delivery edge of said semicircular casing anvil, whereby-material delivered from between said roller and said casing anvil joins a column of air traveling in substantially the same direction, a second portion of said casing being acovering for said separating wheel and being adapted to guide the mixed air and delivered material as a rotating annular column of a crosssectional area substantially equal to the crosssectional area of the column at said delivery edge, said wheel being adapted to rotate in the same direction as the column, said wheel having a series of radial plates substantially equal in area and arranged in series, the last plate or each with mounted beating hammers, a substantially semicircular casing anvil adjacent thereto and partially surrounding said rotor and having a supply channel for the admission of material to be ground and having a delivery edge for delivering ground material where said roller separates from said semicircular casing anvil and a receiving edge for material to be re-ground where said rollerrejoins said semicircular casing anvil, asharp beating edge at said receiving edge radially adjustable with respect to said rotor, an air entrance pipe substantially tangential to said roller at said delivery edge of said casing anvil, an adjustable pivoted damper having its axis parallel to that of said roller, one portion of said damper being adjacent said roller at a point between said delivery edge and said receiving edge, another portion of said damper being a flap adapted to modify the current of mixed air and delivered particles, and separating means adapted to extract a portion of the delivered particles from the stream of mixed air and delivered particles and to return the extracted particles to said rotor between said damper and said beating edge for regrinding.

AUGUST SCHAICH.

CERTIFICATE or CORRECTION. Patent No. 2,270,115. January 15, 19!;2.

AUGUST SCHAICH.

It is hereby certified thnt error appears in me printed specification of the above numbered patent requiring correctionas follows: Page 2,i irst column, line 9, line 12 two occurrences, and lines 17, 20 and. 22, claim 1, for "roller" read --rotor--; and line 55, same claim, before "series" insert "circumferentially groupeii"; eecond column, lineslpand 5, same cleim, and lines 7, 15, 16, 20, 22 and 23, -claim 2, for "rollerfreafi --rotor--; and that the said Letters Patent shouldbe readwith this correction therein that thesame may conform to the record of the case in the Patent Office. 4 I I Signed and sealed this 5rd day of march, A. n. 19h2.

Henry Van Arsdale, Acting commissioner of Patents.

(Seal) 

